Global Variables store information referenced and manipulated by the model. Variables are global, meaning they can be seen and changed by the action of any entity from anywhere in the model. Variables can be set, incremented, decremented, and examined in the Action tab of the dialog — Access and use variables in many fields in dialogs throughout ProcessModel.
Values written to a variable are summarized in the output tables, may be plotted to a time-series graph, summarized in a histogram, and exported to Excel.
Examples of variable usage
Variables record changes during the simulation
To see the volume of people in a waiting room over time, INC (increment) a variable when people arrive and DEC (decrement) when people leave.
A plot of the variable shows the value over time. Charts such as the one below are easily accessible and valuable for uncovering opportunities. See How do I use Smart Stats?
A variable changed in one area of the model allows a gate to open and close in another model area.
Several Model Objects provide the functionality of a gate. Each of the gate model objects (1-11) uses a variable to signal when the gate opens and closes. The variable combines with a trigger activity and a Wait Until statement. See What is a Trigger Activity? What is a Wait Until statement? What is a Model Object?
Variables hold the value of an entity’s name.
Many situations require a change-over or setup if the product changes. To track changes, the value of the past product must be stored in a variable and compared to the current product. If the product is different, then perform a setup.
An explanation of the previous example follows. Every entity entering this activity checks its current name (a_Name) against the value of the last name stored in a variable (v_PreviousName). If the name does not match, a setup time occurs, and the new name replaces the previous name in the variable. See the articles: What is an IF-Then statement? What is an Attribute? What is a Time statement?
Variables used in fields
Use variables in fields to modify information, such as times, or to check values to determine actions.
The largest variable values ProcessModel can use is: 2,147,483,647.
Display user-defined variables on the scoreboard or in a user-defined position during the simulation.